\name{HierHard}
\alias{HierHard}
\title{The Hierarchical  Hard Core Point Process Model}
\description{
Creates an instance of the hierarchical hard core point process model
which can then be fitted to point pattern data.
}
\usage{
  HierHard(hradii=NULL, types=NULL, archy=NULL)
}
\arguments{
  \item{hradii}{Optional matrix of hard core distances}
  \item{types}{Optional; vector of all possible types (i.e. the possible levels
    of the \code{marks} variable in the data)}
  \item{archy}{Optional: the hierarchical order. See Details.}
}
\value{
  An object of class \code{"interact"}
  describing the interpoint interaction
  structure of the hierarchical hard core process with
  hard core distances \eqn{hradii[i,j]}.
}
\details{
  This is a hierarchical point process model
  for a multitype point pattern
  (\ifelse{latex}{\out{H{\"o}gmander}}{Hogmander} and 
  \ifelse{latex}{\out{S{\"a}rkk{\"a}}}{Sarkka}, 1999;
  Grabarnik and \ifelse{latex}{\out{S\"{a}rkk\"{a}}}{Sarkka}, 2009).
  It is appropriate for analysing multitype point pattern data
  in which the types are ordered so that
  the points of type \eqn{j} depend on the points of type
  \eqn{1,2,\ldots,j-1}{1,2,...,j-1}.
  
  The hierarchical version of the (stationary) 
   hard core process with \eqn{m} types, with
  hard core distances \eqn{h_{ij}}{h[i,j]} and 
  parameters \eqn{\beta_j}{beta[j]}, is a point process
  in which each point of type \eqn{j}
  contributes a factor \eqn{\beta_j}{beta[j]} to the 
  probability density of the point pattern.
  If any pair of points
  of types \eqn{i} and \eqn{j} lies closer than \eqn{h_{ij}}{h[i,j]}
  units apart, the configuration of points is impossible (probability
  density zero).
  
  The nonstationary hierarchical  hard core
  process is similar except that 
  the contribution of each individual point \eqn{x_i}{x[i]}
  is a function \eqn{\beta(x_i)}{beta(x[i])}
  of location and type, rather than a constant beta. 
 
  The function \code{\link{ppm}()},
  which fits point process models to 
  point pattern data, requires an argument 
  of class \code{"interact"} describing the interpoint interaction
  structure of the model to be fitted. 
  The appropriate description of the hierarchical
  hard core process pairwise interaction is
  yielded by the function \code{HierHard()}. See the examples below.

  The argument \code{types} need not be specified in normal use.
  It will be determined automatically from the point pattern data set
  to which the HierHard interaction is applied,
  when the user calls \code{\link{ppm}}. 
  However, the user should be confident that
  the ordering of types in the dataset corresponds to the ordering of
  rows and columns in the matrix \code{radii}.

  The argument \code{archy} can be used to specify a hierarchical
  ordering of the types. It can be either a vector of integers
  or a character vector matching the possible types.
  The default is the sequence
  \eqn{1,2, \ldots, m}{1,2, ..., m} meaning that type \eqn{j}
  depends on types \eqn{1,2, \ldots, j-1}{1,2, ..., j-1}.
  
  The matrix \code{iradii} must be square, with entries
  which are either positive numbers, or zero or \code{NA}. 
  A value of zero or \code{NA} indicates that no hard core interaction term
  should be included for this combination of types.
  
  Note that only the hard core distances are
  specified in \code{HierHard}.  The canonical
  parameters \eqn{\log(\beta_j)}{log(beta[j])} 
  are estimated by
  \code{\link{ppm}()}, not fixed in \code{HierHard()}.
}
\seealso{
  \code{\link{MultiHard}} for the corresponding
  symmetrical interaction.

  \code{\link{HierStrauss}},
  \code{\link{HierStraussHard}}.
}
\examples{
   h <- matrix(c(4, NA, 10, 15), 2, 2)
   HierHard(h)
   # prints a sensible description of itself
   ppm(ants ~1, HierHard(h))
   # fit the stationary hierarchical hard core process to ants data
}
\author{\adrian
  
  ,
  \rolf
  
  and \ege.
}
\references{
  Grabarnik, P. and \ifelse{latex}{\out{S\"{a}rkk\"{a}}}{Sarkka}, A. (2009)
  Modelling the spatial structure of forest stands by
  multivariate point processes with hierarchical interactions.
  \emph{Ecological Modelling} \bold{220}, 1232--1240.

  \ifelse{latex}{\out{H{\"o}gmander}}{Hogmander}, H. and 
  \ifelse{latex}{\out{S{\"a}rkk{\"a}}}{Sarkka}, A. (1999)
  Multitype spatial point patterns with hierarchical interactions.
  \emph{Biometrics} \bold{55}, 1051--1058.
}
\keyword{spatial}
\keyword{models}
